Circuit board assembly

ABSTRACT

A circuit board assembly includes a circuit board and at least one electrical element. The circuit board includes a dielectric substrate including a supporting surface, and at least one connecting part formed on the supporting surface. The at least one electrical element is electrically connected to the at least one connecting part via a connecting media. At least one air-exhaust hole extends through the connecting part and the dielectric substrate. The at least one air-exhaust hole is configured for exhausting air from the connecting media.

CROSS REFERENCE

This application is a divisional application of patent application Ser. No. 11/861,661 filed on Sep. 26, 2007 from which it claims the benefit of priority under 35 U.S.C. 120. The patent application Ser. No. 11/861,661 in turn claims the benefit of priority under 35 USC 119 from Chinese Patent Application 200710200532.X, filed on Apr. 27, 2007.

BACKGROUND

1. Technical Field

The present disclosure relates to circuit board assemblies and, particularly, to a circuit board assembly with solder-open defects.

2. Description of the Related Art

Nowadays, electrical connections used in circuit board assemblies typically include soldered connections and conductive-adhesive connections. Welded connection parts such as soldering spots are preformed on a circuit board assembly, and electrical elements are fixed on the soldering spots with solder. The circuit board assemblies with the electrical elements are then transferred to a high-temperature furnace to be heated. The solder is melted to form electrical connections between the electrical elements and the circuit board. Adhesive connecting parts such as gilt layers are preformed on the circuit board, and the electrical elements are attached to the connecting part by conductive adhesives. The circuit board assemblies are then heated to solidify the conductive adhesive. In this way, electrical connections are formed between the electrical elements and the circuit board.

However, poorly applied gilding or scuffing of the connecting part may occur. As a result, recesses may be formed in the connecting part. During assembly of the circuit board assemblies, air may be trapped in the recesses, leading to bad contact states or solder-open defects. A solder-open defect is a condition where there is too little or no solder at an intended solder joint to form a proper connection.

Therefore, it is desirable to provide a circuit board assembly which can overcome the above-mentioned problems.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present circuit board assembly could be better understood with reference to the accompanying drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the circuit board assembly. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.

FIG. 1 is a schematic cross-section view of a first embodiment of a circuit board assembly.

FIG. 2 is a schematic cross-section view of the assembled circuit board assembly shown in FIG. 1.

FIG. 3 is a schematic cross-section view of a second embodiment of a circuit board assembly.

FIG. 4 is a schematic cross-section view of the assembled circuit board assembly shown in FIG. 3.

FIG. 5 is a schematic cross-section view of one embodiment of an electrical element shown in a camera module.

DETAILED DESCRIPTION

Referring to FIGS. 1 and 2, a first embodiment of a circuit board assembly 100 includes a circuit board 10, an electrical element 20 and a connecting media 28. The electrical element 20 is electrically connected to the circuit board 10 via the connecting media 28. A material of the connecting media 28 can be solder or conductive adhesive. In this present embodiment, the connecting media 28 is a soldering material.

The electrical element 20 includes at least one connecting pin 22 inserted into the connecting media 28 to establish a good electrical-contact between the circuit board 10 and the electrical element 20. The material of the at least one connecting pin 22 can be a metal, such as gold or copper. In this present embodiment, the electrical element 20 may be, for example, a resistor, a capacitor, or an image sensor.

The circuit board 10 includes a dielectric substrate 12 and a connecting part 14. The dielectric substrate 12 includes a cavity and a supporting surface 13 communicating with the cavity. The connecting part 14 is received in the cavity and supported on the supporting surface 13 of the dielectric substrate 12. The connecting pin 22 of the electrical element 20 is electrically connected to the connecting part 14 of the circuit board 10 by the connecting media 28.

In this present embodiment, the connecting part 14 is received within the cavity without extending out of the cavity. A material of the connecting part 14 is gold. Alternatively, the connecting part 14 may extend out of the cavity. The connecting part 14 may be a multi-layer metallic layer including a copper layer formed on the supporting surface 13, a nickel layer formed on the copper layer, and a gold layer formed on the nickel layer.

The connecting part 14 is provided with an air-exhaust hole 16 extending through the connecting part 14 and the dielectric substrate 12. A diameter of the air-exhaust hole 16 can be approximately 1 millimeter. The air-exhaust hole 16 is configured for exhausting air from the connecting media 28. It is understood that the number of the air-exhaust holes 16 may be two or more, depending on requirements.

A recess 25 may be formed in the connecting part 14 due to bad gilts or scuffs of the connecting part 14. During assembly of the circuit board assembly 100, air may be trapped in the recess 25. If left in this condition bad contact states or solder-open defects could occur so the following is performed.

Referring to FIG. 2 again, when soldering the electrical element 20 to the connecting part 14, a reflow process is used to ensure the connecting pin 22 attaches to the connecting part 14 by the connecting media 28. Thus, the electrical element 20 is firmly fixed and electrically connected to the connecting part 14. Air accommodated in the recess 25 is expelled out of the circuit board assembly 100 via the air-exhaust hole 16 and the recess 25 is filled by the connecting media 28. Therefore, the bad contact states or the solder-open defects can be prevented. Accordingly, a compact electrical connection between the electrical element 20 and the circuit board assembly 100 is achieved.

Further, to prevent excessive connecting media 28 from causing solder-short defects, (a condition where two adjacent electrical contacts, which are not intended to be connected, are connected due to excess application of solder) the air-exhaust hole 16 may accommodate the excess connecting media 28.

Referring to FIGS. 3 and 4, a second embodiment of a circuit board assembly 200 is similar to the first embodiment of the circuit board assembly 100 except the circuit board assembly 200 includes a first circuit board 21 and a second circuit board 30. The electrical element 20 is electrically connected to the first circuit board 21, and the first circuit board 21 is electrically connected to the second circuit board 30.

At least one of the first circuit board 21 and the second board 30 has a structure similar to that of the circuit board 10 in the first embodiment. In the present embodiment, the second circuit board 30 has a structure similar to that of the circuit board 10 described in the first embodiment.

The first circuit board 21 includes a first dielectric substrate 22 and a first connecting part 24 formed on the dielectric substrate 22. The second circuit board 30 includes a second dielectric substrate 32 and a second connecting part 34 formed on the second dielectric substrate 32. The first connecting part 24 of the first circuit board 21 correspondingly faces the second connecting part 34 of the second circuit board 30. The second circuit board 30 is provided with at least one air-exhaust hole 36. The at least one air-exhausting hole 36 extends through the second connecting part 34 and the second dielectric substrate 32 and is configured for exhausting air trapped in the recess 35. A connecting media 38 is positioned between the first connecting part 24 of the first circuit board 21 and the second connecting part 34 of the second circuit board 30.

The advantages of the circuit board assembly 200 of the second embodiment are similar to that of the circuit board assembly 100 of the first embodiment.

Referring to FIG. 5, a camera module 300 is taken as an example of an application of the second embodiment of the electrical element 20. The camera module 300 includes a lens barrel 50, a holder 52, and an image chip 60. The image chip 60 is electrically connected to the first circuit board 21 of the circuit board assembly 200. Pins (not shown) of the image chip 60 acting as the connecting pins 22 of the electrical element 20 are soldered to the connecting parts 24 and 34 by the connecting media 38. A lens group 55 is received in the lens barrel 50. The holder 52 has a first end 53 and a second end 54. The lens barrel 50 is engaged with the first end 53 of the holder 52. The second end 54 of the holder is attached to the first circuit board 21.

Understandably, the camera module 300 can also be attached to the first embodiment of the circuit board 10.

The above-described example of the electrical element 20 is for better understanding of the present disclosure. Variations may be made to the example without departing from the spirit of the present disclosure as claimed.

Because the connecting part is provided with an air-exhaust hole through the connecting part and the dielectric substrate, air trapped in the recess can flow out of the circuit board assembly via the air-exhaust hole. Therefore, poor contact or the solder-open defects can effectively be eliminated so that a compact electrical connection between the electrical element and the circuit board assembly is maintained. Further, the air-exhaust hole may accommodate the excessive connecting media and thus also improve the solder-short defect.

It will be understood that the above particular embodiments and methods are shown and described by way of illustration only. The principles and the features of the present disclosure may be employed in various and numerous embodiments thereof without departing from the scope of the disclosure as claimed. The above-described embodiments illustrate the scope of the disclosure but do not restrict the scope of the disclosure. 

1. A circuit board assembly comprising: a first circuit board, the first circuit board comprising a first dielectric substrate and at least one first connecting part forming on the first dielectric substrate; a second circuit board comprising a second dielectric substrate and at least one second connecting part, the second dielectric substrate comprising a supporting surface, the at least one second connecting part being formed on the supporting surface, facing the at least one first connecting part, and electrically connecting to the at least one first connecting part via a connecting media, wherein the at least one second connecting part defines at least one air-exhaust hole extending through the at least one second connecting part and the second dielectric substrate, to exhaust air from the connecting media.
 2. The circuit board assembly as claimed in claim 1, further comprising an electrical element electrically connected to the first circuit board.
 3. The circuit board assembly as claimed in claim 2, wherein the electrical element is a camera module comprising an image chip electrically connected to the first circuit board.
 4. The circuit board assembly as claimed in claim 3, wherein the camera module further comprises a holder with at least one lens and the image chip received therein; the image chip is electrically connected to the first connecting part via the connecting media.
 5. The circuit board assembly as claimed in claim 4, wherein the holder is installed on the first circuit board.
 6. The circuit board assembly as claimed in claim 1, wherein the first dielectric substrate defines a first cavity facing the second dielectric substrate, and a first electrical connecting part is formed in the first cavity.
 7. The circuit board assembly as claimed in claim 6, wherein the supporting surface of the second dielectric substrate defines a second cavity and a second electrical connecting part formed in the second cavity; the connecting media is disposed between the first electrical connecting part and the second electrical connecting part. 